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Perfect slide exposure using manual metering

Does anyone use spotmeters for slide exposure? I know black&white photographers prefer spotmeters to measure the contrast range. But how about slides?

If you use either spot- or incident-metering for your slides, I would like to hear from you and learn from your technique. Do you get "perfect exposure"? By perfect, I mean, if you bracketed plus minus 1 stops in increments of 1/2 and consistently found the center exposure to be the best.

It is pretty easy to achieve "good exposure", but only if you bracket can you judge whether you are able to get "perfect exposure" on a consistent basis.

So what's your technique?

-- Andreas Carl, September 10, 2000


I use a spotmeter for colour slides. Works fine and with a +/- 0.5 stop bracket I usually get the exposure I want. Nine times out of ten, I would say.

Is that exposure the centre one? Well, sometimes yes and sometimes no. But its not worth worrying about, IMHO, because there is no such thing as a "perfect" exposure.

The closest you can get objectively to "perfect" is an exposure which captures the entire dynamic range of the scene on film, from the deepest blacks to the brightest highlights.

However, that may not be what you want. There's always some leeway depending on personal preference and there may be more than one exposure which is acceptable - one person's nicely exposed sky is another's underexposed foreground (depends on the subject or what part of the image you want to emphasise). You may want intentionally to create a slightly bright or dark image, depending on your interpretation of the scene.

There's also the question of end product. If you project slides, you might routinely pick a slightly dense slide to give slightly richer colours. On the other hand, if you want a reversal print, many people find that picking a slightly light slide gives the best results because the print seems to end up 0.3-0.5 stops darker than the original. For this reason, I often end up with more than one "keep" from a bracket series.

Technique: various, depending on subject. Any number of good photography books will tell you the basics - after that its experience which you have to learn. If there are some delicate light tones I want to keep, they'll dictate the upper limit of the exposure - the exposure will have to be based on those and everything else will have to fall where it may. Similarly, any dark tones I want to preserve will dictate the lower limit. If I want detail in light and dark areas, averaging the two might be a good starting point. Otherwise, I "eyeball" an average tone and take a meter reading off that as a starting point.

Next, measure the contrast range. If it's too "high" for the film, something will have to give (lose detail in highlight or shadow) or you'll have to resort to meaures to control it. These include graduated filters, using supplementary lighting, reflectors, pull- processing, or just waiting for the sun to move round or for a cloud to cover the sun. There are various treatments you can use for dealing with low contrast as well.

After all that, decide on exposure, factoring in mood you want to create, emphasis you want to place, etc. If the scene is low contrast, there's likely to be more than one acceptable exposure so you may be able to get away without bracketing. If the contrast is high, there may be little or no leeway and bracketing would be sensible.

I don't believe even professionals will get the central bracket every time - this is one reason they shoot Polaroid tests. Or in the studio, have the film developed there and then, while the setup is still in place, compensate the exposure accordingly, then just shoot away at the determined setting.

By the way, I also own an incident meter, but could never get consistent results out of it. It only works when the entire subject is evenly illuminated mostly from the front, as far as I can tell, which is rather restrictive. Any vaguely interesting lighting condition will give trouble - sidelighting will be dodgy and backlighting is right out. Save your groats, get a spotmeter and if you wa

-- Mark Brown, September 11, 2000

I describe my technique on my Spot Metering page. I usually take several readings to know/adjust where different tones are falling.

Regarding my ability to set perfect exposure, on "obsessively metered" shots that are also bracketed, maybe in 50% cases I choose the center exposure later.

-- Vadim Makarov, September 11, 2000


I use a handheld spotmeter for transparencies all the time in preference to the meter in my Bronica's prism, and the meter in my Mamiya 7. The results I get for my landscapes and urban landscapes are fine, exposure -wise. Like a poster above, I can't say that the best of a series is *always* the first but this does happen enough to make me feel that the calibration of the meter is ok and that my technique is competent.

I have a Sekonic 508 which gives a 1 degree spot and though there is a zoom facility I use this narrowest angle of acceptance nearly all the time.

Firstly I look at the scene carefully and decide how I want to treat it viv a vis how it looks "naturally". Part of this will involve deciding what if any filters I want to use over the whole image- for me, that's just really a question of whether I want to use a polariser or warm-up. If so I dial in the appropriate filter factor to the meter which I use in "aperture priority" mode. So for example if I have the meter set at f11 and I want to polarise I'll set the meter to f22. More of this later.

Then I take a reading from an area that I'll plan to approximate to a mid-tone in the transparency - bearing in mind that this may not always be a mid-tone in "real life". Noting the result in my mind, I'll then take readings from the brightest and darkest areas of the scene in which I want to hold detail and ensure that this falls within the range that my film (generally Velvia or Provia 100F) will cope with. If over 2.5 stops of variation is indicated in either direction I'll consider whether and if so what density of ND grad I can use to effectively reduce the brightness range, and fit this to the camera. I may occasionally use a ND grad when the brightness range does fall within that the film can cope with if I want to compress the range further in the interests of balance.

Sometimes of course the brightest area is not the sky or foreground and there may be nothing I can do about it. This provokes a re-appraisal and sometimes a change in my decision regarding how to treat the area I've previously designated a mid-tone.

At this point I'll set my selected aperture and shutter speed on the camera, and check for DOF which might cause me to make adjustments that generally won't affect the amount of light hitting the film.

Finally before making an exposure I take further spot readings from round the scene which I reference back against the setting I've used along the lines of "this will be one stop brighter than a mid-tone, ok? this will be a stop and a half darker than a mid-tone, ok?" After making the occasional re-appraisal that this produces, I'm waiting for the light. The entirety of this is cumbersome to write about but actually pretty quick to do once you have it routinised.

So why doesn't it work perfectly all the time? Well firstly because I make mistakes, both technical and judgmental. I hope I don't make lots of them but I surely make them. Secondly because although I try hard to take my readings and make my judgments in the same light as I'll use for the exposure, sometimes this just doesn't work out. This is especially true when you have been waiting for ever for the one beam of sunlight you're going to get in the next hour in places like Scotland or the English Lake District, or where the light is changing rapidly such as dawn or dusk. Then there's the question of exposures falling about half way between two half-stops. Finally there's a difficulty in setting accurate filter adjustments on a meter that only allows you to adjust aperture in full stops, and I also find that the effect of a polariser varies with angle to the sun and with altitude. I know a lot of people will disagree and say that the polariser has the same 1.5 or 2 stops difference whenever, but that is not my experience. Some of these minor inconveniences can be overcome by the fact that the meter gives an output down to 1/10 stop, so if for example your base reading is f11.3 you have the choice of up or down according to the real effect the filters have in those precise circumstances.

So yes, I bracket.

Finally I've personally not had much joy from incident metering. It seems to me that spotmetering will cover just about everything you'll come across whereas there are clear circumstances where incident metering is not really appropriate and some where it just won't work with any precision at all. I have therefore chosen to concentrate my efforts on what I consider to be a more versatile technique.

-- David Henderson, September 11, 2000

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